The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Driveshafts (or propshafts) are typically employed to transmit rotary power in a drive line, such as, for example, between a transmission or transfer case and a front or rear axle. Modern automotive driveshafts are commonly formed from steel or aluminum tubing. A traditional driveshaft tube may have three primary dimensions including length, outer diameter, and wall thickness. The length of the tube is typically determined by the distance between a transmission output shaft and an axle input shaft. The outer diameter and wall thickness of the driveshaft tube typically depend on the critical speed and torsional strength requirements. Conventional driveshaft tubes have a constant wall thickness.
Maintaining a desired critical speed and torsional strength is typically achieved at the expense of vehicle packaging. Decreasing the outer diameter and/or wall thickness of a conventionally designed driveshaft decreases the area moment of inertia (critical speed is proportional to the square root of area moment of inertia) and torsional strength, and thereby adversely affects the critical speed and vibration attenuation properties. Accordingly, the conventional driveshaft often requires a relatively large outer diameter and wall thickness to achieve the desired critical speed.
In light of the foregoing, there remains a need in the art for a driveshaft that provides for improved vehicle packaging, while maintaining or improving the critical speed, stiffness, and vibration attenuation properties of the driveshaft. The teachings of the present disclosure allow a driveshaft having a reduced outer diameter to improve vehicle packaging without adversely affecting critical speed, torsional yield strength, or vibration damping properties.